AVS 50th International Symposium
    Thin Films Monday Sessions
       Session TF-MoM

Paper TF-MoM4
Incorporation and Control of Silica in Hafnium Silicates using Atomic Layer Deposition Techniques

Monday, November 3, 2003, 9:20 am, Room 329

Session: Atomic Layer Deposition
Presenter: M.N. Rocklein, University of Colorado
Authors: M.N. Rocklein, University of Colorado
F.H. Fabreguette, University of Colorado
S.M. George, University of Colorado
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HfO@sub 2@ and hafnium silicates are leading high-k candidates for replacing SiO@sub 2@ as the gate dielectric in MOSFETs. Advantages of incorporating silica in HfO@sub 2@ are to reduce the interfacial oxide and to prevent crystallization. Very few studies have reported incorporation of silica in HfO@sub 2@ by atomic layer deposition (ALD). We have investigated a new silicon precursor for hafnium silicate ALD. Although sequential exposures of this Si-precursor and H@sub 2@O will not lead to continuous SiO@sub 2@ ALD, growth of hafnium silicates is possible by mixing this Si-precursor and H@sub 2@O exposures together with HfO@sub 2@ ALD from 200 - 260 °C. HfO@sub 2@ ALD is conducted using tetrakis-diethylamidohafnium (TDEAH). Compositional control of the hafnium silicate Hf@sub x@Si@sub (1-x)@O@sub 2@ is achieved by controlling the relative number of Si-precursor/H@sub 2@O and TDEAH/H@sub 2@O reaction cycles. Silica incorporation and control is demonstrated using quartz crystal microbalance (QCM), transmission Fourier tranform infrared (FTIR) spectroscopy and x-ray photoelectron spectroscopy (XPS) investigations. Various reactant exposure sequences yield SiO@sub 2@ content ranging from 0 - 70 %. Hafnium silicate growth rates are also measured and confirmed using a variety of techniques including QCM, spectroscopic ellipsometry, and x-ray reflectance (XRR). Growth rates decrease with increasing SiO@sub 2@ content and vary from 0.65 Å/cycle at 21% SiO@sub 2@ to 0.18 Å/cycle at 67% SiO@sub 2@.